1. Field of the Invention
The present invention relates to a plating apparatus of semiconductor wafer and, more particularly, to a plating apparatus of semiconductor wafer comprising stirring means for a plating solution within a plating tank.
2. Description of the Related Art
As a type of plating apparatus of semiconductor wafer there is available what is called a cup type plating apparatus. The cup type plating apparatus comprises a plating tank, which has an opening in its top part, and a wafer support portion provided along the opening. And the plating tank comprises a solution supply pipe connected to the bottom of the tank as means for circulating a plating solution and a solution discharge passage formed on a side surface of the plating tank in a position near the top opening. The plating solution is supplied from the solution supply pipe to the interior of the plating tank and discharged from the solution discharge passage to outside the plating tank. In performing plating, with a target plating surface of a wafer directed toward the interior of the plating tank, the wafer is placed on the wafer support portion. And in this condition, plating is performed by bringing the plating solution supplied to the interior of the plating tank into contact with the target plating surface of the wafer.
In such a cup type plating apparatus as described above, various improvements have been made in order to realize higher-quality plating treatment. For example, there is a cup type plating apparatus provided with stirring means within a plating tank in order to ensure more uniform plating treatment of a peripheral portion of a target plating surface (refer to the Japanese Patent Laid-Open No. 2001-64795). This stirring means is provided in order to prevent the stagnation of a plating solution in a corner portion formed between the peripheral region of the target plating surface of a wafer and a solution discharge passage located below the peripheral region. That is, when the stirring means is operated, the plating solution is stirred and the stagnation of the plating solution in the corner portion is prevented. When the stagnation is prevented, the peripheral region of the target plating surface adjacent to the corner portion is subjected to more uniform plating treatment.
Incidentally, these days in the fabrication and treatment of wafers, it has been a frequent practice that the wafer surface is subjected to very fine interconnect fabrication. In association with this, it has been necessary to use a technique which allows more uniform plating treatment to be performed on the whole area of a wafer surface having micro-interconnections. For example, such a plating treatment technique as described above is required in the plating treatment for filling the gaps present between the micro-interconnections on the wafer surface.
However, the stirring means of the above-described conventional cup type plating apparatus is used exclusively to improve the plating treatment condition of the peripheral region of a target plating surface, and not to improve the plating treatment of the whole area of a target plating surface.
Furthermore, in recent years, with the progress in the wafer fabrication technology, wafers to be plated themselves have been upsized. And in association with this, the area of a target plating surface has become wider than before. Accordingly, there is a growing need for a technique which enables the plating treatment of the whole area of a wider target plating surface to be more positively and uniformly carried out.
The present invention was made in view of such problems as described above, and it is the object of the invention to provide a plating apparatus which enables the whole area of a target plating surface of a wafer to be subjected to more uniform plating treatment and moreover enables a target plating surface of a wider area to be subjected to positive and uniform plating treatment.